I love general look of the True Necrarchs (Lore-Friendly Version) mod, it's a great change to the bland model introduced in the Blood lines update. I wanted give him the staff that Master Necromancer uses though, so I created a mod like that for my private use. In the comment section for the mod, I noticed a few people asking for a version with a different staff, so I thought others might like to know how to do it. I also recently uploaded a submod that implements the staff change, so if you are not at all interested in modding you can grab that instead: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1570516789&searchtext= If you are even a tiny bit interested in how mods are made though, you might as well start with a minor change like this one.

It's a pretty trivial change to make if you use the Pack File Manager (download link in many modding guides) and shouldn't take you more than a few minutes. Unless you fumble, which you might if you're not familiar with how PFM and the .pack files work. Spend a good 5-10 minutes reading the basic modding guides so you know how to activate the True Necrarchs mod in the PFM, that's pretty much all the modding know-how you need. The rest is just knowing what you need to change, and what you need to change it into.

Use the PFM to create a new .pack file from File -> New. Then click Files -> Add -> From Pack, then find the True Necrarchs mod. The mod is file is under the folder steamapps>workshop>content>594570>1569183458. Choose it, right click at the root. The different branches of the mod appear in PFM in green now. File -> Save as, give the new mod file any name you like that's not a name of a mod file you're using. The branch text should be black now.

With the new mod file open in the PFM, under both the variantmeshdefinitions and variantmeshes>variantmeshdefinitions categories you will find files called vmp_bloodline_necrach_lord_campaign_01.variantmeshdefinition. You have to right click it, and choose Open and Open as Text. (You need to do this on both files as far as I know)

There's a portion pretty low in the opened text field that reads <SLOT name="weapon_5" attach_point="be_prop_5" >. The line below that starts with <VARIANT_MESH model and has a long text with lots of underscores (this symbol: _ ) and Kemmler's name towards the end of the line. You need to replace that whole line with
<VARIANT_MESH model="VariantMeshes\wh_variantmodels\hu1\vmp\vmp_props\vmp_necromancer_staff_1h_01.rigid_model_v2" >

Remember to do it with both files inside the mod.

In PFM, choose File -> Save. Exit PFM, move your new mod file to Total War Warhammer 2's data folder, tick it in the mod manager, and you're good to go.